From d077c3b8d106e7e102a5a58a8a07ed381ff06567 Mon Sep 17 00:00:00 2001
From: Matt Zimmerman <mdz@users.noreply.github.com>
Date: Mon, 28 Feb 2022 11:31:34 -0800
Subject: [PATCH] Add sensor to expose Powerwall backup reserve percentage
 (#66393)

---
 .../components/powerwall/__init__.py          |  1 +
 homeassistant/components/powerwall/models.py  |  1 +
 homeassistant/components/powerwall/sensor.py  | 25 ++++++++++++++++++-
 tests/components/powerwall/mocks.py           |  5 ++++
 tests/components/powerwall/test_sensor.py     | 12 +++++++++
 5 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/homeassistant/components/powerwall/__init__.py b/homeassistant/components/powerwall/__init__.py
index 10504e2aa06..d2850330b7a 100644
--- a/homeassistant/components/powerwall/__init__.py
+++ b/homeassistant/components/powerwall/__init__.py
@@ -229,6 +229,7 @@ def _fetch_powerwall_data(power_wall: Powerwall) -> PowerwallData:
         meters=power_wall.get_meters(),
         grid_services_active=power_wall.is_grid_services_active(),
         grid_status=power_wall.get_grid_status(),
+        backup_reserve=power_wall.get_backup_reserve_percentage(),
     )
 
 
diff --git a/homeassistant/components/powerwall/models.py b/homeassistant/components/powerwall/models.py
index 472d9e59304..cb9b84be16a 100644
--- a/homeassistant/components/powerwall/models.py
+++ b/homeassistant/components/powerwall/models.py
@@ -38,6 +38,7 @@ class PowerwallData:
     meters: MetersAggregates
     grid_services_active: bool
     grid_status: GridStatus
+    backup_reserve: float
 
 
 class PowerwallRuntimeData(TypedDict):
diff --git a/homeassistant/components/powerwall/sensor.py b/homeassistant/components/powerwall/sensor.py
index bc8ab1c0215..9efa5f380dd 100644
--- a/homeassistant/components/powerwall/sensor.py
+++ b/homeassistant/components/powerwall/sensor.py
@@ -45,7 +45,11 @@ async def async_setup_entry(
         | PowerWallImportSensor
         | PowerWallExportSensor
         | PowerWallChargeSensor
-    ] = [PowerWallChargeSensor(powerwall_data)]
+        | PowerWallBackupReserveSensor
+    ] = [
+        PowerWallChargeSensor(powerwall_data),
+        PowerWallBackupReserveSensor(powerwall_data),
+    ]
 
     for meter in data.meters.meters:
         entities.extend(
@@ -111,6 +115,25 @@ class PowerWallEnergySensor(PowerWallEntity, SensorEntity):
         }
 
 
+class PowerWallBackupReserveSensor(PowerWallEntity, SensorEntity):
+    """Representation of the Powerwall backup reserve setting."""
+
+    _attr_name = "Powerwall Backup Reserve"
+    _attr_state_class = SensorStateClass.MEASUREMENT
+    _attr_native_unit_of_measurement = PERCENTAGE
+    _attr_device_class = SensorDeviceClass.BATTERY
+
+    @property
+    def unique_id(self) -> str:
+        """Device Uniqueid."""
+        return f"{self.base_unique_id}_backup_reserve"
+
+    @property
+    def native_value(self) -> int:
+        """Get the current value in percentage."""
+        return round(self.data.backup_reserve)
+
+
 class PowerWallEnergyDirectionSensor(PowerWallEntity, SensorEntity):
     """Representation of an Powerwall Direction Energy sensor."""
 
diff --git a/tests/components/powerwall/mocks.py b/tests/components/powerwall/mocks.py
index 1eac0319819..ae6601b0215 100644
--- a/tests/components/powerwall/mocks.py
+++ b/tests/components/powerwall/mocks.py
@@ -37,6 +37,7 @@ async def _mock_powerwall_with_fixtures(hass):
         status=PowerwallStatus(status),
         device_type=DeviceType(device_type["device_type"]),
         serial_numbers=["TG0123456789AB", "TG9876543210BA"],
+        backup_reserve_percentage=15.0,
     )
 
 
@@ -50,6 +51,7 @@ def _mock_powerwall_return_value(
     status=None,
     device_type=None,
     serial_numbers=None,
+    backup_reserve_percentage=None,
 ):
     powerwall_mock = MagicMock(Powerwall("1.2.3.4"))
     powerwall_mock.get_site_info = Mock(return_value=site_info)
@@ -60,6 +62,9 @@ def _mock_powerwall_return_value(
     powerwall_mock.get_status = Mock(return_value=status)
     powerwall_mock.get_device_type = Mock(return_value=device_type)
     powerwall_mock.get_serial_numbers = Mock(return_value=serial_numbers)
+    powerwall_mock.get_backup_reserve_percentage = Mock(
+        return_value=backup_reserve_percentage
+    )
     powerwall_mock.is_grid_services_active = Mock(return_value=grid_services_active)
 
     return powerwall_mock
diff --git a/tests/components/powerwall/test_sensor.py b/tests/components/powerwall/test_sensor.py
index 33c186e922c..9ff5bd19e39 100644
--- a/tests/components/powerwall/test_sensor.py
+++ b/tests/components/powerwall/test_sensor.py
@@ -121,3 +121,15 @@ async def test_sensors(hass):
     # HA changes the implementation and a new one appears
     for key, value in expected_attributes.items():
         assert state.attributes[key] == value
+
+    state = hass.states.get("sensor.powerwall_backup_reserve")
+    assert state.state == "15"
+    expected_attributes = {
+        "unit_of_measurement": PERCENTAGE,
+        "friendly_name": "Powerwall Backup Reserve",
+        "device_class": "battery",
+    }
+    # Only test for a subset of attributes in case
+    # HA changes the implementation and a new one appears
+    for key, value in expected_attributes.items():
+        assert state.attributes[key] == value